Engine system control responsive to oxygen concentration estimated from engine cylinder pressure

ABSTRACT

Methods of engine system control responsive to oxygen concentration estimated from engine cylinder pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/529,512 filed Aug. 31, 2011.

TECHNICAL FIELD

The field to which the disclosure generally relates includes enginesystem monitoring and control.

BACKGROUND

An internal combustion engine system may include an engine withcylinders defining combustion chambers in which gases and fuel arecombusted for conversion into mechanical power. The system also mayinclude an air induction system for conveying induction gases to thecylinders, and an exhaust system for conveying exhaust gases away fromthe cylinders. The system further may include various system sensors incommunication with one or more controllers to adjust engine fueling,aspirating, and ignition timing to optimize engine performance in termsof fuel consumption, exhaust gas emissions, and output power.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION

One embodiment of a method includes sensing pressure within a cylinderof an engine in an engine system, and estimating oxygen concentration inthe engine system responsive to the sensed pressure within the cylinder.

Another embodiment of a method includes determining a boost pressuredeviation between a boost pressure setpoint and an actual boostpressure, and determining an oxygen concentration deviation between anoxygen concentration setpoint and an estimated oxygen concentration thatis estimated from actual cylinder pressure. The method also includesproducing an oxygen concentration control output in response to theoxygen concentration deviation, and producing a boost control output inresponse to the boost pressure deviation and the oxygen concentrationcontrol output.

A further embodiment of a method includes determining an oxygenconcentration deviation between an oxygen concentration setpoint and anestimated oxygen concentration that is estimated from actual cylinderpressure, and determining a boost pressure deviation between a boostpressure setpoint and an actual boost pressure. The method also includesproducing a boost pressure control output in response to the boostpressure deviation, and producing an oxygen concentration control outputin response to the oxygen concentration deviation and the boost pressurecontrol output.

Also disclosed are various embodiments of products and computer programproducts to implement one or more of the method embodiments above.

Other exemplary embodiments of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whiledisclosing exemplary embodiments of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will become more fullyunderstood from the detailed description and the accompanying drawings,wherein:

FIG. 1 illustrates a schematic of an embodiment of an internalcombustion engine system with a multitude of sensors;

FIG. 2 illustrates a schematic of an embodiment of a control scheme forthe internal combustion engine system of FIG. 1;

FIG. 3 illustrates a schematic of another embodiment of a control schemefor the internal combustion engine system of FIG. 1; and

FIG. 4 illustrates a schematic of an additional embodiment of a controlscheme for the internal combustion engine system of FIG. 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of the embodiments is merely exemplary innature and is in no way intended to limit the invention, itsapplication, or uses.

Disclosed are various embodiments of methods of engine system controlresponsive to oxygen concentration estimated from engine cylinderpressure. For example, an embodiment of a method includes sensingpressure within a cylinder of an engine in an engine system, andestimating oxygen concentration in the engine system responsive to thesensed pressure within the cylinder.

Another embodiment of a method includes determining a boost pressuredeviation between a boost pressure setpoint and an actual boostpressure, and determining an oxygen concentration deviation between anoxygen concentration setpoint and an estimated oxygen concentration thatis estimated from actual cylinder pressure. The method also includesproducing an oxygen concentration control output in response to theoxygen concentration deviation, and producing a boost control output inresponse to the boost pressure deviation and the oxygen concentrationcontrol output. The oxygen concentration control output may be used toadjust an engine system device, for example, a turbocharger variableturbine geometry actuator, a turbocharger EGR bypass valve, and/or thelike.

A further embodiment of a method includes determining an oxygenconcentration deviation between an oxygen concentration setpoint and anestimated oxygen concentration that is estimated from actual cylinderpressure, and determining a boost pressure deviation between a boostpressure setpoint and an actual boost pressure. The method also includesproducing a boost pressure control output in response to the boostpressure deviation, and producing an oxygen concentration control outputin response to the oxygen concentration deviation and the boost pressurecontrol output. The oxygen concentration control output may be used toadjust an engine system device, for example, an exhaust gasrecirculation valve, throttle valve, and/or the like.

Referring now to FIG. 1, the methods may be used in conjunction with aninternal combustion engine system 10. In general, the system 10 includesan internal combustion engine 12 to develop mechanical power fromcombustion of a mixture of air and fuel, an intake or aspiration system14 to provide air to the engine 12, and an exhaust system 16 to conveycombustion gases generally away from the engine 12. Also, the system 10may include a turbocharger 18 in communication across the aspiration andexhaust systems 14, 16 to compress air for combustion to increase engineoutput. The turbocharger 18 may be a variable geometry turbine type ofturbocharger. Those skilled in the art will recognize that a fuel system(not shown) may be used to provide fuel to the engine, and that acontrol system 100 may include one or more suitable processors andmemory (not separately shown) to carry out at least some portions of themethods disclosed herein.

The internal combustion engine 12 may be any suitable type of engine,such as an autoignition engine like a diesel engine, or a spark ignitionengine like a gasoline engine. The internal combustion engine 12 may useany type of suitable liquid or gaseous fuel. The engine 12 includescylinders 25 and pistons in a block (not separately shown) that, alongwith a cylinder head (not separately shown), define combustion chambers(not separately shown). The engine 12 also may include several sensors.For example, an oil pressure sensor 20 may be provided in the block tomeasure engine oil pressure, as well as an engine speed and/or positionsensor 22 to measure the rotational speed and/or position of an enginecrankshaft (not shown). Also, a coolant temperature sensor 24 in theblock measures the temperature of engine coolant flowing therethrough.

Finally, the engine 12 may include a number of engine cylinder pressuresensors 26 in communication with the engine cylinders 25 to measurepressure therein. The pressure sensors 26 may be located in immediatecommunication with the engine cylinders 25, such as for estimatingparameters related to the engine's combustion curve. The engine cylinderpressure sensors 26 may be separate devices or may be integrated intoother devices, such as pressure-sensing glow-plugs (PSGs).

Also, the pressure sensors 26 may be located in upstream or downstreamcommunication with the engine cylinders 25, such as for estimatingparameters related to the engine's gas exchange pressure curve (e.g.during opening of intake and exhaust valves). For example, the pressuresensors 26 may be placed in upstream communication in any suitablelocation in the aspiration system 14, such as in communication with theintake manifold 36. In another example, the pressure sensors 26 may beplaced in downstream communication in any suitable location in theexhaust system 16, such as in communication with the exhaust manifold50.

Although the cylinder pressure sensors 26 may be used in accordance withthe methods described herein, they typically may be used to enhanceengine system control and/or diagnostics. For example, the cylinderpressure sensors 26 may enhance control of cylinder-to-cylinder timingand fueling to compensate for individual cylinder differences. Thecylinder pressure sensors 26 also may be used to compensate for fueloctane and cetane differences, and they may be used to perform closedloop ignition control using advanced combustion techniques such asHomogeneous Charge Compression Ignition (HCCI). As will be describedfurther herein below, the methods described herein take advantage of theexistence of these cylinder pressure sensors 26 to estimate oxygenconcentration in the intake manifold 36 and/or in the engine cylinders25.

The aspiration system 14 may include, in addition to suitable conduitand connectors, an air filter 28 to filter incoming air, a turbochargercompressor 30 to compress the filtered air, an intercooler 32 to coolthe compressed air, and a throttle valve 34 to throttle the flow of thecooled air. The aspiration system 14 also may include an intake manifold36 to receive the throttled air and distribute it to the combustionchambers of the engine 12.

The aspiration system 14 also may include a number of sensors. Forexample, an intake manifold pressure sensor 38 may be provided incommunication with the intake manifold 36 to measure the pressure of airflowing to the engine cylinders 25, and a temperature sensor 40 tomeasure the temperature of air flowing to the cylinders 25. A mass airflow sensor 42 and ambient temperature sensor 44 may be placeddownstream of the air filter 28 and upstream of the turbochargercompressor 30. A speed sensor 46 may be suitably coupled to theturbocharger compressor 30 to measure the rotational speed thereof. Athrottle position sensor 48, such as an integrated angular positionsensor, may be used to measure the position of the throttle valve 34.

The exhaust system 16 may include, in addition to suitable conduit andconnectors, an exhaust manifold 50 to collect exhaust gases from thecombustion chambers of the engine 12 and convey them downstream to therest of the exhaust system 16. The exhaust system 16 also may include aturbocharger turbine 52 in downstream communication with the exhaustmanifold 50, a catalytic converter 54 such as a close-coupled dieseloxidation catalyst (DOC) device, and a turbo wastegate valve 56 tocontrol bypass of exhaust gases around the turbocharger turbine 52 tothe DOC unit. Also, the exhaust system 16 may include a nitrogen oxide(NOx) adsorber unit 58 upstream of a soot filter 60, which may beupstream of an exhaust tailpipe 62.

Additionally, the exhaust and/or aspiration system(s) 16, 14 may includean exhaust gas recirculation (EGR) apparatus 64 to recirculate exhaustgas from the exhaust manifold 50 of the engine 12 to the intake manifold36 of the engine 12. The EGR apparatus 64 may include an EGR coolerbypass valve 66 in downstream communication with the exhaust manifold 50to control recirculation of exhaust gases back to the intake manifold36, an EGR cooler 68 downstream of the EGR cooler bypass valve 66 tocool EGR gases, and an EGR valve 70 to control flow of the EGR gases.The EGR apparatus 64 also may include an EGR mixing unit 72 incommunication with the EGR valve 70 at a location downstream of thethrottle valve 34 and upstream of the intake manifold 36 to mix EGRgases with the throttled air.

Also, as used herein, HP EGR may include a high pressure exhaust gasrecirculation path between exhaust and induction subsystems upstream ofa turbocharger turbine and downstream of a turbocharger compressor, andLP EGR may include a low pressure exhaust gas recirculation path betweenexhaust and induction subsystems downstream of the turbocharger turbineand upstream of the turbocharger compressor.

The exhaust system 16 may further include a number of sensors. Aposition sensor 74 may be disposed in proximity to the turbocharger 18to measure the position of the variable geometry turbine, and a NOxsensor 75 may be placed downstream of the turbine 52. Temperaturesensors 76, 78 may be placed upstream and downstream of the catalyticconverter 54 to measure the temperature of exhaust gases at the inletand outlet of the catalytic converter 54. An oxygen (O₂) sensor 80 maybe placed upstream of the adsorber unit 58 to measure oxygen in theexhaust gases. One or more pressure sensors 82 may be placed across thesoot filter 60 to measure the pressure drop thereacross. A tailpipetemperature sensor 84 may be placed just upstream of a tailpipe outletto measure the temperature of the exhaust gases exiting the exhaustsystem 16. Finally, a position sensor 86 may be used to measure theposition of the EGR cooler bypass valve 66, and another position sensor88 may be used to measure the position of the EGR valve 70.

In addition to the sensors shown and discussed herein, any othersuitable sensors and their associated parameters may be encompassed bythe presently disclosed methods. For example, the sensors could alsoinclude accelerator pedal sensors, vehicle speed sensors, powertrainspeed sensors, filter sensors, flow sensors, vibration sensors, knocksensors, intake and exhaust pressure sensors, turbocharger speed andnoise sensors, and/or the like. Moreover, other engine system parametersmay be encompassed by the presently disclosed methods, includingturbocharger efficiency, component fouling or balancing problems, filterloading, Diesel Particulate Filter (DPF) regeneration status, EGR rate,HP/LP EGR fraction or ratio, cylinder charge mal-distribution, and/orthe like. In other words, any sensors may be used to sense any suitablephysical parameters including electrical, mechanical, and/or chemicalparameters. As used herein, the term sensor includes any suitablehardware and/or software used to sense any engine system parameter.

According to one embodiment, however, oxygen sensors may not be used inthe intake manifold 36 or in the engine cylinders 25. Accordingly, thecost and complexity of using such sensors may be avoided.

The control system 100 may receive and process input from the varioussensors in light of stored instructions and/or data, and transmit outputsignals to various actuators. The control system 100 may include, forexample, an electrical circuit, an electronic circuit or chip, and/or acomputer. In an illustrative computer embodiment, the control system 100generally may include one or more processors, memory devices that may becoupled to the processor(s), and one or more interfaces coupling theprocessor(s) to one or more other devices. Although not shown, theprocessor(s) and other powered system devices may be supplied withelectricity by a power supply, for example, one or more batteries, fuelcells, or the like.

The processor(s) may execute instructions that provide at least some ofthe functionality for the disclosed system 10 and methods. As usedherein, the term instructions may include, for example, control logic,computer software and/or firmware, programmable instructions, or othersuitable instructions. The processor may include, for example, one ormore microprocessors, microcontrollers, application specific integratedcircuits, programmable logic devices, field programmable gate arrays,and/or any other suitable type of electronic processing device(s).

Also, the memory device may be configured to provide storage for datareceived by or loaded to the engine system, and/or forprocessor-executable instructions. The data and/or instructions may bestored, for example, as look-up tables, formulas, algorithms, maps,models, and/or any other suitable format. The memory may include, forexample, RAM, ROM, EPROM, and/or any other suitable type of storagearticle and/or device.

Further, the interfaces may include, for example, analog/digital ordigital/analog converters, signal conditioners, amplifiers, filters,other electronic devices or software modules, and/or any other suitableinterfaces. The interfaces may conform to, for example, RS-232,parallel, small computer system interface, universal serial bus, CAN,MOST, LIN, FlexRay, and/or any other suitable protocol(s). Theinterfaces may include circuits, software, firmware, or any other deviceto assist or enable the control system 100 in communicating with otherdevices.

The methods or parts thereof may be implemented in a computer programproduct including instructions carried on a computer readable medium foruse by one or more processors to implement one or more of the methodsteps. The computer program product may include one or more softwareprograms comprised of program instructions in source code, object code,executable code or other formats; one or more firmware programs; orhardware description language (HDL) files; and any program related data.The data may include data structures, look-up tables, or data in anyother suitable format. The program instructions may include programmodules, routines, programs, objects, components, and/or the like. Thecomputer program may be executed on one processor or on multipleprocessors in communication with one another.

The program(s) can be embodied on computer readable media, which caninclude one or more storage devices, articles of manufacture, or thelike. Illustrative computer readable media include computer systemmemory, e.g. RAM (random access memory), ROM (read only memory);semiconductor memory, e.g. EPROM (erasable, programmable ROM), EEPROM(electrically erasable, programmable ROM), flash memory; magnetic oroptical disks or tapes; and/or the like. The computer readable mediumalso may include computer to computer connections, for example, whendata is transferred or provided over a network or another communicationsconnection (either wired, wireless, or a combination thereof). Anycombination(s) of the above examples is also included within the scopeof the computer-readable media. It is therefore to be understood thatthe method may be at least partially performed by any electronicarticles and/or devices capable of executing instructions correspondingto one or more steps of the disclosed methods.

FIG. 2 illustrates an illustrative embodiment of a control architectureor system 200 that may be used wholly or partially to implement one ormore engine control methods. This embodiment is similar in many respectsto the embodiment of FIG. 1 and like numerals between the embodimentsgenerally designate like or corresponding elements throughout theseveral views of the drawing figures. Additionally, the descriptions ofthe embodiments are incorporated by reference into one another and thecommon subject matter generally may not be repeated here.

The system 200 or method may include closed-loop control of any of oneor more engine system devices, for example, one or more EGR valves 270.The system 200 also may include the engine 10 and the cylinder pressuresensors 26. The cylinder pressure sensor(s) 26 may produce one or moresignals for use in producing an oxygen concentration estimate 202.

Oxygen concentration may have the most direct effect on good engineoperation, and may have a significant effect on the shape of cylinderpressure during combustion. Thus, oxygen concentration may be estimatedreliably from cylinder pressuring sensing. The oxygen concentrationestimate 202 may be produced by a model, calculation, equation, formula,circuit, and/or any other suitable device, expedient, or the like.

Cylinder pressure may be correlated to oxygen concentration in anysuitable manner. First, an engine system may be operated in aninstrumented vehicle on a vehicle test track, on a dynamometer, in anemissions test laboratory, and/or the like. During engine systemoperation, cylinder pressure may be sensed using engine cylinderpressure sensors in communication with engine cylinders of an engine ofthe engine system. Then, oxygen concentration may be sensed using one ormore oxygen sensors in the engine intake manifold and/or one or moreengine cylinders. Values for any or all of the sensed parameters may bestored in any suitable manner for subsequent data analysis.

The various parameters may be analyzed or evaluated to correlate enginecylinder pressure to oxygen concentration in the engine system. Suchcorrelation may be carried out in any suitable fashion. For example,cylinder pressure may be formulaically related to oxygen concentration.In another example, cylinder pressure may be empirically andstatistically related to oxygen concentration. In any case, thecorrelation or relationship between cylinder pressure and oxygenconcentration may be modeled formulaically, empirically, acoustically,and/or the like. For example, empirical models may be developed fromsuitable testing and can include lookup tables, maps, and the like thatmay cross reference cylinder pressure with oxygen concentration.

As used herein, the term “model” may include any construct thatrepresents something using variables, such as a look up table, map,formula, algorithm and/or the like. Models may be application specificand particular to the exact design and performance specifications of anygiven engine system. In one example, the engine system models in turnmay be responsive to engine speed and intake manifold pressure andtemperature. The engine system models may be updated each time engineparameters change, and may be multi-dimensional look up tables usinginputs including engine speed and engine intake gas density or oxygenconcentration, which may be determined with the intake pressure,temperature, and universal gas constant.

In one example, the frequency content of the cylinder pressure sensorsignals may be analyzed or evaluated to estimate the other engine systemparameters. For example, the frequency spectrum of the cylinder pressuresensor signals or portions thereof may be analyzed to determine theoxygen concentration, for example, using Fourier analysis, Laplaceanalysis, Wavelet analysis, and/or the like. Also, such preprocessingmay be coupled with, for example, model-based or artificial intelligenceapproaches like neural networks to evaluate relationships between sensedengine cylinder pressure and oxygen concentration.

Accordingly, engine cylinder pressure measurements are used as a proxyfor and, thus, to replace or augment measurements of, oxygenconcentration. Although cylinder pressure at any given moment duringengine operation may be measured, one preferred aspect includes usingnon-combustion cylinder pressure measurements such as pre-combustionand/or post-combustion pressure. More particularly, engine cylinderpressure may be sensed just before combustion, but substantially whencompression is complete.

The system 200 or method may include an oxygen concentration setpoint204, an arithmetic node 206 to produce a deviation between the setpoint204 and the oxygen concentration estimate 202, and an oxygenconcentration based closed-loop controller 208 that may produce aclosed-loop oxygen concentration setpoint in response to the deviation.The node 206 may perform any suitable arithmetic operation on thesetpoint like summing, subtraction, superimposing, averaging, and/or anyother suitable combination. The closed-loop controller 208 may produceas output a closed-loop command or setpoint for any suitable enginesystem device, for example, an actuator position command for an EGRvalve 270. The closed-loop controller 208 may include one or more of aproportional controller, proportional-integral controller,proportional-derivative controller, proportional-integral-derivativecontroller, or any other suitable type of controller that may beseparate, or integrated in one controller or on one processor in anysuitable manner. As indicated by an arrow, the controller 208 mayreceive as additional input, one or more additional parameters of anysuitable type.

In operation, pressure may be sensed within one or more of the cylinders25 of the engine 12 of the engine system 10, oxygen concentration may beestimated in the engine system 10 responsive to the sensed pressurewithin the cylinder(s) 25, and the engine system 10 may be controlledresponsive to the estimated oxygen concentration. More particularly, anoxygen concentration deviation may be determined between an oxygenconcentration setpoint and an estimated oxygen concentration that isestimated from actual cylinder pressure. Then, an oxygen concentrationcontrol output may be produced in response to the oxygen concentrationdeviation, and that output may be used to control one or more enginesystem devices, for example, the EGR valve 270, an engine throttlevalve, or the like. Accordingly, oxygen concentration in the intakemanifold 36 and/or the engine cylinders 25 may be controlled in a tightand responsive manner.

The oxygen concentration may be an estimate from oxygen concentration inthe engine cylinder and/or in an intake manifold of the engine system.Also, the oxygen concentration may be estimated by analyzing frequencyof the sensed pressure and correlating the frequency with oxygenconcentration.

FIG. 3 illustrates an illustrative embodiment of a boost control system300 that may be used wholly or partially to implement one or more boostcontrol methods. This embodiment is similar in many respects to theembodiment of FIGS. 1 and 2 and like numerals between the embodimentsgenerally designate like or corresponding elements throughout theseveral views of the drawing figures. Additionally, the descriptions ofthe embodiments are incorporated by reference into one another and thecommon subject matter generally may not be repeated here.

The system 300 or method may include closed-loop control of any suitableengine system device 356, for example, an actuator for a variableturbine geometry turbocharger, a turbocharger inlet valve, aturbocharger bypass or wastegate valve, or any other suitable device.The system 300 also may include the engine 10 and one or moreturbocharger boost pressure sensors 302 and the cylinder pressuresensors 26 placed in any suitable location. The boost pressure sensor(s)302 may produce one or more signals for actual boost pressure, and thecylinder pressure sensor(s) 26 may produce one or more signals for usein producing the oxygen concentration estimate 202.

The system 300 or method may include a boost pressure setpoint 304, anarithmetic node 306 to produce a deviation between the setpoint 304 andthe actual boost pressure from the sensor(s) 302, and a boost pressureclosed-loop controller 308 that may produce a closed-loop boost controlsetpoint in response to the boost pressure deviation. The node 306 mayperform any suitable arithmetic operation on the setpoint and signallike summing, subtraction, superimposing, averaging, and/or any othersuitable combination. The closed-loop controller 308 may produce asoutput a closed-loop command or setpoint, like an actuator positioncommand for the boost control device 356. The closed-loop controller 308may include a proportional controller, a proportional-integralcontroller, a proportional-derivative controller, aproportional-integral-derivative controller, or any other suitable typeof controller that may be separate, or integrated in one controller oron one processor in any suitable manner. As indicated by the arrow, thecontroller 308 may receive as additional input, one or more additionalparameters of any suitable type. Additionally, the controller 308receives output from the oxygen concentration based controller 208.

In operation, a boost pressure deviation is determined between a boostpressure setpoint and an actual boost pressure, and an oxygenconcentration deviation is determined between an oxygen concentrationsetpoint and an estimated oxygen concentration that is estimated fromactual cylinder pressure. Then, an oxygen concentration control outputis produced in response to the oxygen concentration deviation.Thereafter, a boost control output is produced in response to the boostpressure deviation and the oxygen concentration control output, and aboost control device is controlled in response to the boost controloutput.

FIG. 4 illustrates an illustrative embodiment of an oxygen concentrationcontrol system 400 that may be used wholly or partially to implement oneor more boost control methods. This embodiment is similar in manyrespects to the embodiment of FIGS. 1 through 3 and like numeralsbetween the embodiments generally designate like or correspondingelements throughout the several views of the drawing figures.Additionally, the descriptions of the embodiments are incorporated byreference into one another and the common subject matter generally maynot be repeated here.

The control system 400 may include the oxygen concentration controller208 and the boost controller 308 of FIG. 3, wherein the boost controller308 may be used as an input to the oxygen concentration controller 208instead of the other way around. Accordingly, in operation, an oxygenconcentration deviation is determined between an oxygen concentrationsetpoint and an estimated oxygen concentration that is estimated fromactual cylinder pressure, and a boost pressure deviation is determinedbetween a boost pressure setpoint and an actual boost pressure. Then, aboost pressure control output is produced in response to the boostpressure deviation. Thereafter, an oxygen concentration control outputis produced in response to the oxygen concentration deviation and theboost pressure control output, and one or more engine system devices,for example, the EGR valve 270, a throttle valve, or the like, may becontrolled in response to the oxygen concentration control output.

With one or more of the embodiments described herein, desired conditionsmay be achieved in an engine intake manifold and/or engine cylindersincluding desired gas composition (primarily oxygen concentration), gastemperature, gas pressure, and/or gas motion (controlled with one ormore swirl valves or the like).

The following is a description of select embodiments within the scope ofthe invention. However, the invention is not limited to the specificembodiments described hereafter, and each embodiment may be used aloneor in any combination with any other embodiment(s) or elements thereof.

Embodiment 1 of the invention may include a method including sensingpressure within a cylinder of an engine in an engine system, andestimating oxygen concentration in the engine system responsive to thesensed pressure within the cylinder.

Embodiment 2 of the invention may include a method as set forth inembodiment 1 and further comprising controlling oxygen concentration inat least one of an engine intake manifold or the engine cylinder inresponse to the estimated oxygen concentration.

Embodiment 3 of the invention may include a method as set forth in oneor more of embodiments 1-2 wherein the estimating step includes at leastone of estimating oxygen concentration in the engine cylinder or in anintake manifold of the engine system.

Embodiment 4 of the invention may include a method as set forth in oneor more of embodiments 1-3 wherein the estimating step includesanalyzing frequency of the sensed pressure and correlating the frequencywith oxygen concentration.

Embodiment 5 of the invention may include a method as set forth in oneor more of embodiments 1-4 wherein the controlling step includesadjusting at least one EGR valve.

Embodiment 6 of the invention may include a method as set forth in oneor more of embodiments 1-5 wherein the controlling step includesadjusting a throttle valve.

Embodiment 7 of the invention may include a program product comprising acomputer-readable medium including instructions executable by acomputer-controlled engine system to cause the system to implement amethod as set forth in one or more of embodiments 1-6.

Embodiment 8 of the invention may include a product including at leastone engine cylinder pressure sensor to measure engine cylinder pressure,at least one memory device storing program instructions and data, and atleast one control system coupled to the sensor and memory and responsiveto the program instructions for causing the computer-controlled systemto perform a method as set forth in one or more of embodiments 1-6.

Embodiment 9 of the invention may include a product as set forth inembodiment 8 wherein the at least one control system includes an oxygenconcentration closed-loop controller.

Embodiment 10 of the invention may include a method includingdetermining a boost pressure deviation between a boost pressure setpointand an actual boost pressure, and determining an oxygen concentrationdeviation between an oxygen concentration setpoint and an estimatedoxygen concentration that is estimated from actual cylinder pressure.According to this embodiment, the method also may include producing anoxygen concentration control output in response to the oxygenconcentration deviation, and producing a boost control output inresponse to the boost pressure deviation and the oxygen concentrationcontrol output.

Embodiment 11 of the invention may include a method as set forth inembodiment 10 and further comprising controlling boost pressureresponsive to the boost control output.

Embodiment 12 of the invention may include a method as set forth in oneor more of embodiments 10-11 wherein the controlling step includesadjusting at least one of a variable turbine geometry actuator or an EGRbypass valve.

Embodiment 13 of the invention may include a method as set forth in oneor more of embodiments 10-12 further comprising sensing pressure in anengine cylinder to provide the actual cylinder pressure, and sensingturbocharger boost pressure to provide the actual boost pressure.

Embodiment 14 of the invention may include a program product comprisinga computer-readable medium including instructions executable by acomputer-controlled engine system to cause the system to implement amethod as set forth in one or more of embodiments 10-13.

Embodiment 15 of the invention may include a product including at leastone engine cylinder pressure sensor to measure engine cylinder pressure,at least one turbocharger boost pressure sensor to measure turbochargerboost pressure, at least one memory device storing program instructionsand data, and at least one control system coupled to the sensors andmemory and responsive to the program instructions for causing thecomputer-controlled system to perform a method as set forth in one ormore of embodiments 10-13.

Embodiment 16 of the invention may include a product as set forth inembodiment 15 wherein the at least one control system includes an oxygenconcentration closed-loop controller, and a boost pressure closed-loopcontroller.

Embodiment 17 of the invention may include a method includingdetermining an oxygen concentration deviation between an oxygenconcentration setpoint and an estimated oxygen concentration that isestimated from actual cylinder pressure, and determining a boostpressure deviation between a boost pressure setpoint and an actual boostpressure. The method of embodiment 17 also may include producing a boostpressure control output in response to the boost pressure deviation, andproducing an oxygen concentration control output in response to theoxygen concentration deviation and the boost pressure control output.

Embodiment 18 of the invention may include a method as set forth inembodiment 17 and further comprising controlling oxygen concentration inat least one of an engine intake manifold or an engine cylinderresponsive to the oxygen concentration control output.

Embodiment 19 of the invention may include a method as set forth in oneor more of embodiments 17-18 further comprising sensing pressure in anengine cylinder to provide the actual cylinder pressure, and sensingturbocharger boost pressure to provide the actual boost pressure.

Embodiment 20 of the invention may include a program product comprisinga computer-readable medium including instructions executable by acomputer-controlled engine system to cause the system to implement amethod as set forth in one or more of embodiments 17-19.

Embodiment 21 of the invention may include a product including at leastone engine cylinder pressure sensor to measure engine cylinder pressure,at least one turbocharger boost pressure sensor to measure turbochargerboost pressure, at least one memory device storing program instructionsand data, and at least one control system coupled to the sensors andmemory and responsive to the program instructions for causing thecomputer-controlled system to perform a method as set forth in one ormore of embodiments 17-19.

Embodiment 22 of the invention may include a product as set forth inembodiment 21 wherein the at least one control system includes an oxygenconcentration closed-loop controller, and a boost pressure closed-loopcontroller.

The above description of embodiments of the invention is merelyexemplary in nature and, thus, variations thereof are not to be regardedas a departure from the spirit and scope of the invention.

What is claimed is:
 1. A method comprising: sensing pressure within acylinder of an engine in an engine system; and estimating oxygenconcentration in the engine system responsive to the sensed pressurewithin the cylinder.
 2. The method of claim 1, further comprisingcontrolling oxygen concentration in at least one of an engine intakemanifold or the engine cylinder in response to the estimated oxygenconcentration.
 3. The method of claim 1, wherein the estimating stepincludes at least one of estimating oxygen concentration in the enginecylinder or in an intake manifold of the engine system.
 4. The method ofclaim 1, wherein the estimating step includes analyzing frequency of thesensed pressure and correlating the frequency with oxygen concentration.5. The method of claim 1, wherein the controlling step includesadjusting at least one EGR valve.
 6. The method of claim 1, wherein thecontrolling step includes adjusting a throttle valve.
 7. A computerprogram product comprising a computer-readable medium includinginstructions executable by a computer-controlled engine system to causethe system to implement a method according to claim
 1. 8. A product,comprising: at least one engine cylinder pressure sensor to measureengine cylinder pressure; at least one memory device storing programinstructions and data; and at least one control system coupled to thesensor and memory and responsive to the program instructions for causingthe computer-controlled system to perform a method according to claim 1.9. The product of claim 8, wherein the at least one control systemincludes an oxygen concentration closed-loop controller.
 10. A methodcomprising: determining a boost pressure deviation between a boostpressure setpoint and an actual boost pressure; determining an oxygenconcentration deviation between an oxygen concentration setpoint and anestimated oxygen concentration that is estimated from actual cylinderpressure; producing an oxygen concentration control output in responseto the oxygen concentration deviation; and producing a boost controloutput in response to the boost pressure deviation and the oxygenconcentration control output.
 11. The method of claim 10, furthercomprising: controlling boost pressure responsive to the boost controloutput.
 12. The method of claim 11, wherein the controlling stepincludes adjusting at least one of a variable turbine geometry actuatoror an EGR bypass valve.
 13. The method of claim 10, further comprising:sensing pressure in an engine cylinder to provide the actual cylinderpressure; and sensing turbocharger boost pressure to provide the actualboost pressure.
 14. A computer program product comprising acomputer-readable medium including instructions executable by acomputer-controlled engine system to cause the system to implement amethod according to claim
 10. 15. A product, comprising: at least oneengine cylinder pressure sensor to measure engine cylinder pressure; atleast one turbocharger boost pressure sensor to measure turbochargerboost pressure; at least one memory device storing program instructionsand data; and at least one control system coupled to the sensors andmemory and responsive to the program instructions for causing thecomputer-controlled system to perform a method according to claim 10.16. The product of claim 15, wherein the at least one control systemincludes an oxygen concentration closed-loop controller, and a boostpressure closed-loop controller.
 17. A method comprising: determining anoxygen concentration deviation between an oxygen concentration setpointand an estimated oxygen concentration that is estimated from actualcylinder pressure; determining a boost pressure deviation between aboost pressure setpoint and an actual boost pressure; producing a boostpressure control output in response to the boost pressure deviation; andproducing an oxygen concentration control output in response to theoxygen concentration deviation and the boost pressure control output.18. The method of claim 17, further comprising: controlling oxygenconcentration in at least one of an engine intake manifold or an enginecylinder responsive to the oxygen concentration control output.
 19. Themethod of claim 17, further comprising: sensing pressure in an enginecylinder to provide the actual cylinder pressure; and sensingturbocharger boost pressure to provide the actual boost pressure.
 20. Acomputer program product comprising a computer-readable medium includinginstructions executable by a computer-controlled engine system to causethe system to implement a method according to claim
 17. 21. A product,comprising: at least one engine cylinder pressure sensor to measureengine cylinder pressure; at least one turbocharger boost pressuresensor to measure turbocharger boost pressure; at least one memorydevice storing program instructions and data; and at least one controlsystem coupled to the sensors and memory and responsive to the programinstructions for causing the computer-controlled system to perform amethod according to claim
 17. 22. The product of claim 21, wherein theat least one control system includes an oxygen concentration closed-loopcontroller, and a boost pressure closed-loop controller.